Process of manufacturing alkaline bicarbonates.



JOHANN GOTTLIEB BEHRENS, OF BREMEN, GERMANY.

PROCESS OF EJEANUFACTUBiNGI ALKALlNE BiCARBQNATES.

Specification of Letters Patent.

Patented Nov. 13, 1906.

Application filed May 19, 1906, Serial No. 317,801-

To all whom it may concern:

' Be it known that I, JOHANN 'GorrLI'EB BEHRENS, a subject of the German Emperor, and a resident of Bremen, Germany, have in wanted an Improved Process of Manufacturing Alkaline Bicarbonates, of which the fol-- lowing is a specification. This invention relates to a process of manu facturing bicarbonate of soda and bicarbon ate of pot-ash by treating anhydrous monocarbonates with a gaseous mixture containing carbon dioxid (carbonic anhydrid) and steam in equimoleoular quantities, this treatment being efi'ected at a high pressure corre sponding to the temperature at which the bicarbonate to be obtained is decomposed.

Alkaline bicarbonates are usually obtained by dissolving the monocarbonate in water and passing a current of carbon dioxid into the solution. There is also another method of manufacturing bicarbonate of soda which consists in passing carbon dioxid. over ordinary crystallized sodium carbonate. According to this method a part of the water of crystallization is separated and in flowing away carries with it the im urities contained in the crude carbonate 0 soda employed. The result is represented thus:

NE COAOILO CO: 2NaI-ICO 911 0.

In the former process a solution of the bicarbona-te is produced, while in the latter the bi carbonate is obtained in a dry state.

' It is specially with a view of obtaining liquid carbon dioxid that the process of manufacturing the bicarbonate in a liquid form is resorted to, as such a solution sets free at boiling temperature onehalf of its content of carbon dioxid, ivhich is obtained in this manner in a state of urity, While monocarbonate remains in so ution, according to the following equation:

ZNaIlCOs NazCOg ILO 002.

form of a dry powder instead of boiling the solution containing only fifteen per cent. of bicarbonate. By thus effecting the dissociation of the dry bicarbonate-powder dry monocarbonate is naturally obtained as residue, which must be again converted into bicarbonate by being caused. to absorb carbon dioxid and Water, according to theXequation:

naooa H O co, 2NaHCQ-i. The practical realization of this last reaction presents great difliculties in view of the fact that success depends substantially on the manner in which the water is caused to enter into the reaction. lnffact, when the dry monocarbonate of soda powder is sprinkled with water it loses its porosity and becomes dense, so that the saturation with the carbon dioxid can only be imperfectly effected. This is the reason why this method of proceeding has not been employed in manufacture. The problem is thus to find a method bywhich dry bicarbonate can be manufactured from anhydrous monocarbonate; Attempts have been made to solve this problem by mixing with the necessary quany tity of steam the comb'ustion-gasesfrom coke,

which contain carbon dioxid for the purpose of effecting a uniform distribution of the Water and in conducting the gases thus saturated to the monocarbonate to be converted.

However, in the specification of the patent taken out for that process it is stated that in order to avoid the condensation of the steam it is necessary that the mixture of gas and steam. should be kept at a temperature of 70 centigrade. Now the inventor of the process forming the subject of the present application and hereinafter described has proved by special experiments that the. dry monocarbonate of soda is not able at a term perature of 70 Centigrade and at atmospheric pressure to absorb carbon dioxid and Water contained in the above-mentioned mixture of combustion-gases and steam, because that temperature is too near the decomposition temperature of the bicarbonate for a reaction to be possible. up these experiments I have, however, proved that it is nevertheless possible to bring about the reaction by causing the mixture of gas and steam to act on the monocarbonate after compressing the mixture. It is on this discovery that the present invention is based. The degree of compression to which it is necessary to resort corresponds naturally to the deco'n'lposition temperature of the bicarbonate, as the pressure of the mixture of carbon dioxid and steam diluted by nitrogen must overcome the tension of In following temperature The success of the reaction is 2 ISL-23%.???

not dependent only on. the pre plays an important part, but 3 2 presence of the nitrogen contrived is the mixture of gaseous products of combustion. 5 In fact, it it were desired to compress a mi eiieeting the treatment of ture of pure carbon dioxid and steiu'rr it is to roonate or soda by carbon dioxid under be feared that in consequence of theiiierease pr ssure in a strong iron chamber. in this of pressure the steam Would be condensed oressuro has only an. accelerating prematurely. For this reason the i no idea is to work Without raising to of an indifferent gas-sin thepresei; Th eectiou takes place fhitrogen -is of greatimportance the A u'ure, although more i must be kept ll ride! all circumstances 1 other hand, it be desired state of Vapor in the compres r v ption oi the carbon dioxid The discovery deseri ed ab corresponding to the x5 ployedeommerci j ture oi the bicarbon ii uid carbon. (iiOkl c to .VOIl-i at the uorinai fo llowing manner: 1. necessary under all diameter arranged horisoi it at a .l'iighcr pressure tity of monocarbonate in the the tension oi the de 20 is so placed as to iii]. the tube to the presei'it process of about one half of its (iii 'ii the previous prochalf of the hamster is left time the absorption, but mit of the passage of the mixture or in essential inproducts of combustion containing V hich the reac- 25 dioxid and the equirrmlecuiar piece. lies the turn steanr, In these tubes the reset ,euce between the two proclace. Thus While in the prose e nown the absorption ofthe caroon dim-mo is effected in principle under normal. stmos- .ssai

3o pherie pressure and at a low "temperature should be and the separation of the carbon diortid at a tious over i high temperature, but under the me to the. ollow ouation: pressure, exactly the reverse tekes pl; in A r #9 the present process, in which the pressure 35 varies, While the temperature remains ti e eircuii'isti'inces an excess of mo sainet hat is to say, the anhydr cam e: avoided, as otherwise the anvbonate in the form of poir i in we powder would absorb this the tubes heated from the out and fiiiVQltibiH'tO aha-rd and stantlymaintained at tbeiiecon 0 4 mass. it obviely stop the reaction. "y of: the absorption of inonocarbonate as which at i'irst sight appears to *iogy to the present process wt, in which the absorption iut the prrjmess con'miercially i ,1, carbon dioxid and Water cted in molecular propor- 5 o perature of the bicarbonate, aim

the mixture of gas and steam t carbon dioxid comes in eoiitec: monocarbonate after having; ciently compressed according to e i 45 les set out above bicarbonate o Lieu, end iorthis reason it is necesno he obtainednotwithstanding r Y co at the required volume or steam is ill-- temperature. If, however, the g red into c mixture oi" combustionlowered, the bicarbonate is quickiy d K "es containing carbon dioxio'. The surest p osed, setting free carbon (liOXlli and i. etc}: i "mplest means 09 attaining the above 56 he latter is eliminated by condi-insation oiled result is to use the exhaust-gases n5 drying, and the pure carbon dioxid remmno ii-m iritr rib-combustionmotoremploying ing is liquefied by coni 'ircsion. The iorges tbatistosay, pro sorption of the carbon dioxid is th mg upon ignited carbon with .tained by the raising of and the setting i v to the following reaction:

5 5' by the lowering of the pressure. This rnndit a (V) fication of the pressure at the same tempe s UT 2 1 ture has the advantage over the modification 'ihese gases when of the temperature at the same pressure (at in ti motor-(Mind r combine according to mos'pheric) of being more convenient, as the the t, rowing equations:

6,0 dr owder is not heated or cooled N 1 I2 Y P I so-ii-i,+o,=eo,+a,o, 5

mixed with air and ignited,

easily varied, Tl'ie process just dos. exiiausegases conta ning carbon dioxid ii 1 enables seve1rty-five per cent. of their couand steam in exact moieeul'ar proportions,

" tent of'carbon dioxid to be taken from the and can consequently be conducted directlj ,65-combustion-gases. to the o'ry nonocarbonate. On the other 530 z i P high to permit oi the occurrence luted with nitrogen there is no danger", even in case of the gaseous mixture being powerfullycompresscd, that any premature condensation of steam will occur. has been stated it will be seen that the special composition of the exhaust-gases from a generator gas-motor furnishes the basis for the better carrying out of the present invention.

In the actual practice of my process it is not essential that the monocarbonatc be.

acted upon by the gaseous mixture mentioned at any particular temperature or pressure, but only that the temperature be suiliciently A of the reaction and the pressure correspondingly high to prevent the decomposition of the bicarbonate at such temperature. Particularly satisfactory results may be obtained by reacting upon the monocarbonate with the exhaust-gases from an internal combustion motor employing generator-gas as a fuel at a temperature of 250 centigradeunder a pres sure equal to three times normal atmospheric pressure. I

The idea of utilizing the exhaust-gases ironi carbonates is not new; but this idea has only been applied in one form, which consists in causing the gas to enter an aqueous solution of monocarbonate in order by absorption to ,separate the carbon dioxid contained in the gaseous mixture. Thus nitrogen plays no part in the reaction, and the quantity of steam in the gases is inappreciable, as the gases are conveyed into an aqueous lye. The

From what a gas-motor for the manufacture of bihand, the exhaust-gases being strongly di I part played by the exhaust-gases in the two methods of application is thus quite difierent.

In the process already known the gases act simply as a source of carbon dioXid, while in the process which forms the subject of the present invention each of the constituent parts of the exhaust-gases plays a special part, the steam and the carbon dioxid entering into the chemical reaction and the nitro-, gen preventing any premature condensation of the steam.

Having fully described my invention, what I claim, and desire to secure by Letters Patent, is

The herein-described process of producing alkaline bicarbonates which consists in relto't ing upon dry alkaline gaseous mixture containing an inactive gas, carbon dioxid and steam, the two latterbeing present in equimolecular proportions, at a high temperature and under a high atmospheric pressure, such pressure being sufiicient to prevent decomposition of the bicarbonate at the temperature at which the reaction occurs, the proportion of the inactive gas in the gaseous mixture being suflicient to prevent the condensation of the steam under the influence of the pressure under which the said reaction occurs, substantially as described.

In testimony whereof I have hereunto set my hand in presence of two witnesses.

JOHANN GOTTLIEB BEHRENS.

monocarbonate with a 

